No, but I can tell you it's on the intake manifold, probably toward the rear
Here are two online sources for you:
For AllData:
http://bit.ly/AllData_Repair_Manuals_Online
Here's the one for Mitchell as well:
http://bit.ly/mitchell_repair_manuals_online
RepairPal Certified shops can diagnose and repair your 1990 Ford Aerostar. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.